Study of orientational ordering in discotic liquid-crystalline thin films by using Fourier transform infra-red spectroscopy

A method of tilting a sample out of the normal incident plane of an infra-red beam has been developed for investigating the arrangement of the various segments of discotics in three dimensions. It is found that the discs of the molecules lie flat on the silicon windows and are arranged in the columns. It is also shown that the C-C stretching vibrations are randomly distributed along the disc. More precise assignment of some of the vibrational bands has been achieved with this method.